Feeding ecology of shallow water meiofauna: insights from a stable isotope tracer experiment in Potter Cove,King George Island, Antarctica

摘要

Antarctic meiofauna is still strongly understud ied, and so is its trophic position in the food web. Primary producers, such as phytoplankton, and bacteria may repre sent important food sources for shallow water metazoans, and the role of meiobenthos in the benthic-pelagic coupling represents an important brick for food web understanding. In a laboratory, feeding experiment ~(l3)C-labeled freeze dried diatoms (Thalassiosira weissflogii) and bacteria were added to retrieved cores from Potter Cove (15-m depth, November 2007) in order to investigate the uptake of 3 main meiofauna taxa: nematodes, copepods and cuma ceans. In the surface sediment layers, nematodes showed no real difference in uptake of both food sources. This outcome was supported by the natural δ~(13)C values and the commu nity genus composition. In the first centimeter layer, the dominant genus was Daptonema which is known to be opportunistic, feeding on both bacteria and diatoms. Cope pods and cumaceans on the other hand appeared to feed more on diatoms than on bacteria. This may point at a bet ter adaptation to input of primary production from the water column. On the other hand, the overall carbon uptake of the given food sources was quite low for all taxa, indicating that likely other food sources might be of relevance for these meiobenthic organisms. Further studies are needed in order to better quantify the carbon requirements of these organisms.